Sheet materials are surfaces in which the length and width of the material determine the over-riding dimensions of the material. Though the thickness of a sheet can be varied, it is substantially less than the other two dimensions. Examples of sheet materials include all varieties of sheet metal, paper and cardstock, textiles and architectural fabrics, various plastics and rubbers, veneers, fiberboards, aerogel, smart materials, etc. Of these, materials like metal, rigid plastics, fiberboards and veneers are relatively stiff sheets while materials like rubbers, softer plastics, aerogel and fabrics are flexible. Though sheet materials can be used in a variety of ways to make useful products, the most interesting use of such materials is to convert the 2-dimensional surface into a 3-dimensional one to perform different functions. Various ways to achieve this are known and are in practice today. These include various methods of 3-dimensional forming like pressing in a mould, rolling, bending in brake presses, attaching to a pre-formed substrate or sub-structure. Softer sheet materials can be hardened into 3-dimensional shapes by various hardening techniques and harder sheet materials can be softened till they become pliable for 3-d forming. Among the more interesting applications of sheet material is the expanded sheet concept, specifically in metal and more recently in some pliable materials, where a slitting pattern enables an expansion of the surface by applying a force like bending, pulling or stretching.